Coronaviridae
| Coronaviridae | |
|---|---|
| Virus classification | |
| Group: | Group IV ((+)ssRNA) |
| Order: | Nidovirales |
| Family: | Coronaviridae |
| Subfamilies and Genera | |
Coronaviridae is a family of enveloped, positive-stranded RNA viruses. The viral genome is 26–32 kb in length. Virions are spherical, 120–160 nm across (Coronavirinae), bacilliform, 170–200 by 75–88 nm (Bafinivirus) or found as a mixture of both, with bacilliform particles characteristically bent into crescents (Torovirus). The particles are typically decorated with large (~20 nm), club- or petal-shaped surface projections (the “peplomers” or “spikes”), which in electron micrographs of spherical particles create an image reminiscent of the solar corona. Members of this family are thus referred to as coronaviruses, as are members of the subfamily Coronavirinae.
The 5' and 3' ends of the genome have a cap and poly (A) tract, respectively. The viral envelope, obtained by budding through membranes of the ER and/or Golgi apparatus, invariably contains two virus-specified (glyco)protein species, S and M. Glycoprotein S comprises the large surface projections, while the M protein is a triple-spanning transmembrane protein. Toroviruses and a select subset of coronaviruses (in particular the members of subgroup A in the genus Betacoronavirus) possess, in addition to the peplomers composed of S, a second type of surface projections composed of the hemagglutinin-esterase protein. Another important structural protein is the phosphoprotein N, which is responsible for the helical symmetry of the nucleocapsid that encloses the genomic RNA.
Group: ssRNA(+)
There are currently a total of 25 species assigned to this family, twenty of which belong to the subfamily Coronavirinae.
Coronaviruses are transmitted by faecal-oral route or by aerosols of respiratory secretions.
Coronaviruses infect a wide range of mammals and birds and occur worldwide. Although most diseases are mild, sometimes they can cause more severe situations in humans, such as, for example, the infection of the respiratory tract known as Severe Acute Respiratory Syndrome (SARS). They can also cause enteric infections in very young infants and, in rare situations, neurological syndromes.
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